<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .myitem-one-list {
            width: 500px;
        }
        
        .ng-star-inserted {
            text-align: center;
        }
        
        .fileinput-button {
            position: relative;
            /* // display: inline-block; */
            overflow: hidden;
            cursor: pointer;
        }
        
        .fileinput-button input {
            position: absolute;
            right: 0px;
            top: -20px;
            opacity: 0;
            -ms-filter: 'alpha(opacity=0)';
            font-size: 50px;
        }
    </style>
</head>

<body>
    <div style="text-align: center;display:inline-block;overflow: hidden;">
        <span class=" fileinput-button">
            <span style="display:inline-block;line-height: 30px">点击上传文件</span>
        <input type="file" onChange="readExcel()" id="myfile01" />
        </span>
    </div>
    <h3>如果上传成功，点击下面可以进行下载</h3>
    <div id="testUpload">

    </div>
    <script>
        function readExcel() {
            let files = document.getElementById('myfile01').files
            console.log(files);
            if (files.length <= 0) { //如果没有文件
                return null;
            } else if (errorFileSize(files[0], '4MB')) {
                console.log('上传格式不正确，文件大小不得超过4mb');
                return null;
            }
            // 测试
            // uploadfile(files[0])
            // return
            const fileReader = new FileReader();
            fileReader.onload = (ev) => {
                try {
                    const data = ev.target.result;
                    console.log('文件读取结果:', data)
                    document.getElementById('testUpload').innerHTML = `<a download="${files[0].name}" href="${data}" style="margin-left:5px;margin-right:5px;"><br><span style="margin-left:5px;margin-right:5px;">${files[0].name}</span></a>`
                } catch (e) {
                    console.log('文件获取出错了~')
                    return null;
                }
            };
            fileReader.readAsDataURL(files[0]);
        }
        /**
         * 限制文件大小，返回 true代表文件格式有误
         * @param {File} file 文件
         * @param {String} limitSize 限制大小
         * 使用方法：limitFileSize(files[0], '1MB')
         */
        function errorFileSize(file, limitSize) {
            var arr = ["KB", "MB", "GB"]
            var limit = limitSize.toUpperCase();
            var limitNum = 0;
            for (var i = 0; i < arr.length; i++) {
                var leval = limit.indexOf(arr[i]);
                if (leval > -1) {
                    limitNum = parseInt(limit.substr(0, leval)) * Math.pow(1024, (i + 1))
                    break
                }
            }
            if (file.size > limitNum) {
                return true
            }
            return false
        }
    </script>
</body>

</html>
